On 11.10 my max allowed resolution is 1024x768, while my monitor supports 1280x800 on windows.

I've seen a method to solve this via xrandr, but I allways get a message saying it fails to get size of gamma.

 xrandr: Failed to get size of gamma for output default
Screen 0: minimum 640 x 480, current 1024 x 768, maximum 1024 x 768
default connected 1024x768+0+0 0mm x 0mm
   1024x768       61.0* 
   800x600        61.0  
   640x480        60.0  

Is there any other way to add 1280x800 resolution to my laptop, any workarounds this?

Thanks in advance.